001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 * 
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 * 
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 * 
019 */
020package org.apache.directory.api.ldap.model.schema.comparators;
021
022
023import org.apache.directory.api.i18n.I18n;
024import org.apache.directory.api.ldap.model.schema.LdapComparator;
025import org.apache.directory.api.util.Strings;
026import org.slf4j.Logger;
027import org.slf4j.LoggerFactory;
028
029
030/**
031 * <p>
032 * A comparator for Words/KeyWords. RFC 4517 par. 4.2.21 (KeywordMatch) and par.
033 * 4.2.32 is pretty vague about the definition of what is a word or a keyword
034 * ("...The precise definition of a word is implementation specific...)
035 * ("...The identification of keywords in the attribute value and the exactness
036 *  of the match are both implementation specific...).
037 * <p>
038 * We will simply check that the assertion is present in the value at some place,
039 * after having deep trimmed the word.
040 * <p>
041 * For instance, the word "  World  " will be found in the value "Hello world!".
042 * <p>
043 * A word is defined by the following regexp : "(^|[^A-Za-z0-9])([A-Za-z0-9])*([^A-Za-z0-9]|$)".
044 * Anything that is not matched by this regexp will not be considered as a word.
045 * 
046 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
047 */
048public class WordComparator extends LdapComparator<String>
049{
050    /** The serial version UID */
051    private static final long serialVersionUID = 2L;
052
053    /** A logger for this class */
054    private static final Logger LOG = LoggerFactory.getLogger( WordComparator.class );
055
056
057    /**
058     * The StringComparator constructor. Its OID is the StringMatch matching
059     * rule OID.
060     * 
061     * @param oid The Comparator's OID
062     */
063    public WordComparator( String oid )
064    {
065        super( oid );
066    }
067
068
069    /**
070     * {@inheritDoc}
071     */
072    public int compare( String value, String assertion )
073    {
074        if ( LOG.isDebugEnabled() )
075        {
076            LOG.debug( I18n.msg( I18n.MSG_13749_COMPARING_STRING, value, assertion ) );
077        }
078
079        if ( value == assertion )
080        {
081            return 0;
082        }
083
084        // -------------------------------------------------------------------
085        // Handle some basis cases
086        // -------------------------------------------------------------------
087        if ( ( value == null ) || ( assertion == null ) )
088        {
089            return ( assertion == null ) ? 1 : -1;
090        }
091
092        // Now, trim the assertion and find it in the value
093        String trimmedAssertion = Strings.trim( assertion );
094        int pos = value.indexOf( trimmedAssertion );
095
096        if ( pos != -1 )
097        {
098            int assertionLength = trimmedAssertion.length();
099
100            // Check that we are not in a middle of some text
101            if ( assertionLength == value.length() )
102            {
103                return 0;
104            }
105
106            if ( pos == 0 )
107            {
108                char after = value.charAt( assertionLength );
109
110                if ( !Character.isLetterOrDigit( after ) )
111                {
112                    return 0;
113                }
114                else
115                {
116                    return -1;
117                }
118            }
119
120            if ( pos + assertionLength == value.length() )
121            {
122                char before = value.charAt( value.length() - assertionLength - 1 );
123
124                if ( !Character.isLetterOrDigit( before ) )
125                {
126                    return 0;
127                }
128                else
129                {
130                    return -1;
131                }
132            }
133
134            char before = value.charAt( value.length() - assertionLength );
135            char after = value.charAt( assertionLength );
136
137            if ( Character.isLetterOrDigit( after ) )
138            {
139                return -1;
140            }
141
142            if ( !Character.isLetterOrDigit( before ) )
143            {
144                return -1;
145            }
146
147            return 0;
148        }
149
150        return -1;
151    }
152}